Bach’s cello suites are among the best known works of classical music, now risking popularization to the point of fatigue as they provide background music for cat food commercials. But one hundred and forty years after the great composer’s death they were virtually unknown, until a young, aspiring Catalan cellist came across them in a musty music shop. Eric Siblin has captured an extraordinary romance–that of Pablo Casals, J.S. Bach, and their mutual obsession with the sonic possibilities of the cello. I put six questions to Siblin about his book, The Cello Suites: J.S. Bach, Pablo Casals, and the Search for a Baroque Masterpiece, now appearing in paperback: